Field Level Auto-inoculation of Sorghum chafer, Pachnoda interrupta (Olivier) (Coleoptera: Scarabaedae) with Metarhizium anisopliae based Microbial Bio-control Agents using Locally Affordable Traps

Sorghum chafer,Pachnoda interrupta, is the most serious pest of sorghum in Ethiopia destroying the entire fields at the milk stage and causing up to 100% yield loss. Current control methods entirely depend on direct spraying and baiting with insecticides which does not provide long lasting control. Efficient biological control agents such as entomopathogenic fungi that can control the pest in the breeding sites need to be developed. Traps equipped with auto-inoculation devices are important alternative methods to spread entomopathogens into insect pest populations. Field studies on fungal auto-inoculation trap development from locally available materials conducted over three feeding and two mating seasons of P. interrupta resulted in two efficient auto-inoculation traps (AIT1 and AIT2) baited with a five compounds blend lure which were not significantly different in catch performance with the standard Japanese beetle trap.  Two selected virulent isolates of Metarhizium anisopliae (PPRC51 and PPRC2) were tested for field efficacy using these two designs of locally affordable auto-inoculation traps loaded with 1gm of dry conidia. Using AIT1, PPRC51 and PPRC2 induced 41% and 40% field mortality respectively, on P. interrupta adults under high temperature and low relative humidity conditions, while highest field viability of the two isolates five days after application was 36 % and 40 % for PPRC51 and PPRC2, respectively. Based on the catch performance, field efficacy and viability data observed, the two AIT’s are recommended for further development to be used with PPRC51 and PPRC2 for augmentation biological control in the pest’s natural habitat as a component of integrated pest management against P. interrupta